If I were going to start a religion—a respectable one—it would sound wise. It would draw crowds. It would work. It would make promises that make sense. It would be a religion of wisdom, power, and glory. It would require all sorts of activities for the worshiper to perform. Eternal life would be something attainable through sincere efforts. Leaders would be accomplished, victorious spiritual elites. Sinners could change their lives and become holy through extraordinary radical acts of service and spiritual practices.
Christianity is different. Our God entered into history and was born in a feeding trough. He lived and performed some miracles but always seemed to be small-time. Then, at the height of his popularity, he willingly subjected himself to Roman execution by crucifixion. This is not the sort of religion I would invent.
Christians have always been tempted to try to make Christianity more appealing. The Christian faith has always been difficult for people. In hopes of appealing to the masses, Christians have at times boasted of other-worldly holiness, this-worldly blessings, health, wealth, prosperity, power, respect, and influence.
Yet, Paul himself tells us that Christians are the weak and foolish things of this world (1 Cor. 1:27). Our holiness appears ridiculous. Our eternal life is hidden in Christ; our visible life, as with all other people, is suffering and death:
For consider your calling, brothers: not many of you were wise according to worldly standards, not many were powerful, not many were of noble birth. But God chose what is foolish in the world to shame the wise; God chose what is weak in the world to shame the strong; God chose what is low and despised in the world, even things that are not, to bring to nothing things that are, so that no human being might boast in the presence of God. (1 Cor. 1:26–29)
The message of the cross is foolishness. This is the point: the very nature of Christianity is not the kind of religion that appeals to human nature. Christianity is the kind of religion whose worshipers boast of no glory and claim no rewards for their efforts. Instead, Christians confess their weakness and sinfulness. God's religion is not the sort of religion I would invent. A famous passage of Scripture says, "For my thoughts are not your thoughts, neither are your ways my ways, declares the LORD. For as the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts" (Isa. 55:8–9) .
Isn't the very character of our weak religion itself evidence that it is not of this world? Isn't the foolishness of the cross a mark that the message is of divine origin? Maybe so, or perhaps the apostles decided to invent the kind of religion that had absolutely no appeal to human nature, as a practical joke. Except—last I heard—martyrs don't joke about that for which they die.